Sputum Conidia Identifying Aspergillus niger Necrotizing Pneumonia

from Infections in Medicine ®
Posted 07/21/2003
Jill A. Nord, MD, Vincent J. La Bombardi, PhD

A 49-year-old homeless man was admitted with productive cough, hemoptysis, fevers, and chills of 4 weeks' duration.
He also had severe weakness, anorexia, and night sweats. He had a long smoking history but denied alcohol or drug

His temperature was 38.6°C (101.5°F); pulse rate, 126 beats per minute; and respiration rate, 30 breaths per minute.
He was emaciated and in respiratory distress and was producing dark brown sputum. Pulmonary examination revealed
diffuse bilateral crackles without wheezing. His leukocyte count was 22,600/µL, and hemoglobin level was 10.7 mg/dL,
with normal values for renal and liver function and electrolytes, including calcium, magnesium, and phosphate. Chest
radiographs revealed right upper and middle lobe infiltrates with lucencies suggestive of cavitations. He required
immediate mechanical ventilation.

Treatment with antituberculous antibiotics, clindamycin and ceftriaxone for possible aspiration pneumonia, and
trimethoprim-sulfamethoxazole for granulomatous Pneumocystis carinii pneumonia was started. Stains of sputum
samples obtained before intubation were negative for acid-fast bacilli. Gram stain of the sputum revealed many
polymorphonuclear leukocytes and an absence of bacteria; however, the sample did contain darkly pigmented, round
structures (conidia, Figure 1, arrow) and multiple pleomorphic crystals (Figure 2, arrow).

Figure 1. (click image to zoom)  

Figure 2. (click image to zoom)  

On the second hospital day, bronchoscopy performed to obtain deep-er specimens revealed dark, viscous pus in the
right main-stem bronchus and left lower lobe. Both sputum and bronchial lavage specimens subsequently grew
Aspergillus niger. Treatment with amphotericin B, 1 mg/kg/d IV, was started on the second hospital day. A tension
pneumothorax required chest tube placement, and the patient remained persistently febrile.

Progressive hypocalcemia developed (calcium level, 5.9 mg/dL; creatinine level, 2.2 mg/dL) on the second hospital
day, and despite calcium carbonate therapy, the patient's serum calcium level fell to 3.7 mg/dL on the sixth hospital
day, with a normal serum magnesium level and an inorganic phosphate level of 6.3 mg/dL. Renal failure, hypotension,
oliguria, and massive hemoptysis developed, and the patient died on the sixth hospital day.

A niger is the third most common Aspergillus species to cause pulmonary disease, after Aspergillus fumigatus and
Aspergillus flavus.[1] It is also a rare cause of chronic necrotizing pulmonary aspergillosis.[1-3] A fermentation
by-product of Aspergillus fungi, especially A niger, is oxalic acid, which complexes with calcium from the host to form
calcium oxalate crystals. These crystals cause severe tissue necrosis, including damage to blood vessels.[4,5]

The diagnosis of an invasive Aspergillus pulmonary infection is normally accomplished by finding hyphal fragments in a
specimen obtained by bronchoscopy. Rarely, as in this case, only conidia are identified.[6] Conidia of A niger are darkly
pigmented and echinulate and have a diameter of 4 to 5 µm.

Cases and photographs submitted by Jill A. Nord, MD, associate professor of clinical medicine, and Vincent J. La
Bombardi, PhD, assistant professor of clinical pathology, Saint Vincent Catholic Medical Centers-St. Vincent's Hospital
Manhattan, New York, and New York Medical College, Valhalla, NY.

Infect Med 20(6):277, 2003. © 2003 Cliggott Publishing, Division of SCP